The Transitive Relation
by Lemon Row
Summary: Sherlock and John share a moment curled up in bed with their newborn son.


**Author's Notes/Warning: **The teenciest, barely-noticeable mention of the process of artificial reproduction methods.

* * *

Sherlock looked down at the little creature that was currently swimming in the river of mattress that separated him from his husband. Flat on its back, arms and legs in the air. Kicking at some imaginary opponent. Tiny digits flexing and extending, grabbing at handfuls of nothing. A pair of glimmering sapphires looking first at him, and then to John, and then at the ceiling before circling back to repeat the circuit.

He frowned. Tilted his head a few degrees to one side. "What does it want, John?"

A puff of laughter unfurled over his cheeks, and he glanced up to see the doctor grinning at him. Clearly, the petite organism resting between them was already having an influence on his partner's attitude; that was the sort of comment that would've normally earned him a more stern expression.

"'He', Sherlock. The question is, what does _he_ want?" Tucking his arm beneath his head, John trailed his index finger over the little squid's chest. "I know we've not quite picked out a name for him yet, but you could at least do him the courtesy of using a more human descriptor than '_it_'." There was the smile again. Barely more than a twitch at the corner of his mouth this time, but still there. "He is our son, after all."

John moved his finger to within reaching distance of its- his… _his_ grasp, and the newborn closed his hand around the bony pillar. "And he doesn't want anything. Not for the moment, at least. Best enjoy _that_ while we can."

"Mm," was the only response Sherlock bothered to offer.

A comfortable blanket of silence settled over them, and Sherlock spent the next few moments watching the interloper make his strange gestures, hoping to perhaps discern some sort of meaning from them.

Now, to say that he was elated by the presence of this newest occupant of 221B Baker Street would be… a slight over-statement. In fact it would be bordering on completely inaccurate.

Growing up, and throughout the entirety of his adult life, Sherlock never had the desire to become a parent.

He still didn't.

This was not something he'd been looking forward to over the last nine months. Anticipating, yes. Of course. There were preparations that had to be made, after all. Legal documents to be signed. Bedrooms to be rearranged and decorated. Foodstuffs to be purchased. Sharp and/or explosive and/or otherwise volatile experiment equipment to put away.

Hopefully not on a permanent basis.

He didn't see why it was necessary to make such an adjustment in the first place. It would be some time before the as-yet-unnamed infant would acquire the ability for voluntary locomotion, so as long as he or John didn't accidentally _place_ him in the vicinity of Sherlock's scientific equipment, there would be no danger.

Surely they could trust each other to follow such a simple guideline, couldn't they?

He'd argued this point with John, of course.

John had nodded, squashed down the grin that attempted to commandeer his mouth, and told Sherlock to clean up his materials.

So, with all he'd had to sacrifice already, and all that he _would _have to sacrifice in the future on behalf of this offspring, why had Sherlock agreed to his birth in the first place?

Because John wished for it. Told him that it was what 'normal' couples did, after being together for as long as they had.

_Eight years, five months, two weeks, four days, and_… Sherlock snuck a look at the alarm clock over John's shoulder. _Sixteen hours_.

…And because they 'aren't getting any younger, that's for sure'.

Sherlock had scoffed at that comment, rolled his eyes, and thanked John most sincerely for stating that which was incredibly obvious. He'd then spent the next few minutes wondering aloud if he'd missed some memo about time no longer being a linear construct.

He'd slept on the sofa that night.

During his continued internal debate on the subject, Sherlock had realized that having an infant in their home _would_ lend itself to the collection of a vast amount of data where concepts of human growth and development were concerned. He doubted that John would appreciate him performing experiments on their son, but… surely he would have no objections to Sherlock making mere _observations_, would he?

The detective was hauled back to the present when John leaned forward and pressed a kiss to their son's brow. Even then, Sherlock could see him smiling as he did it. A second later, he felt the ex-soldier hook his leg over his own, twining their lower limbs together. "He's _ours_, Sherlock," he murmured.

Sherlock looked up at his husband, and was compelled to mirror his expression with a smile of his own. John being happy tended to inspire the same emotion within him. Especially when he was _this_ happy.

Hearing him give a little huff through his nose, Sherlock found his attention diverted back down to the baby boy. John's words were still echoing through the catacombs of his mind, eventually clamouring against the walls of his visual cortex. At that, his eyes were called into action. Performing the same meticulous examination of the tiny human's features as they would any crime scene. Documenting the slope of his forehead, the cut of his nose, the mould of his jaw.

He didn't have to glance up to know he'd find the shadow of the same imprints on his husband's face.

In that instant, he knew.

He already knew.

Nothing had been easy about selecting the surrogate mother for their son. Sherlock had insisted that their approach to choosing her be as scientific, logical, and detailed as the one they used to solve their cases. He had drawn up a set of criteria that would allow them to select the best candidate to be the donor of half their child's genetic constitution. Included in the list were such factors as the woman's health, intelligence, and family medical history.

John had argued with him on it a little, of course. Saying that having and raising a child was as much of an art as it was a science. When he'd come to understand though that this was simply Sherlock's way of showing that he cared, of trying his best to do right by their future child, the doctor had eased back on his criticism.

The knowledge that Sherlock would go ahead and do it anyway had probably played a small part in his retreat, too.

While their process for selecting the right mother for their child had been long, arduous, and precise, the one for choosing which of them would be the father was… less so.

Though he knew there was a much more accurate and dignified way of explaining it, John had been telling people that they'd essentially 'tossed our collective seeds into a paper sack, given it a good shake, and picked one out at random'. Their method was such that a DNA test would be required to determine which of the two of them was the father.

Sherlock had it though. The answer. He knew. It was, after all, staring right at him.

"Actually, John… as it turns out… he's _yours_." There wasn't a hint of resentment, or even a whisper of regret in Sherlock's voice as he said those words.

…It wasn't there because he didn't feel it. That paternal possession over the little humanoid beansprout squirming between them. He didn't have the same fatherly love for this child that John did. He wouldn't even if they _did_ share each other's genes.

Oh, he cared for him, absolutely. The infant was a part of Sherlock's family unit now. A part of his List of People.

If anyone so much as lifted a pair of scissors to a single hair on their son's head without asking permission first, he would ensure that Britain's entire military force was brought down on them in the same instant.

No, it wasn't that he didn't care for the little turnip-head. The problem was simply that at the moment, he just had nothing to connect to. Barely more than a week old, right now their son had the intelligence and charisma of a teacup.

Looking around the room as he was, their son was seeing everything, and yet nothing. He was a sheet of paper that had yet to be written on. A block of clay that hadn't been transformed by an artist's hands. He had no hopes, no desires, no thoughts beyond that which instinct dictated. Not a speck of understanding about anything in the world around him.

Oh, the potential was there for all those things, sure. But potential was of little meaning until it was actually put to use.

Quite simply, Sherlock just had nothing to connect to. No way of communicating with the little one.

He had a hard enough time forging relationships with fully grown human beings; what hope did he have with one that had existed for less than ten days, and whose communication skills amounted to the random vibration of air against his vocal cords?

When he'd first visited their son in the hospital, he'd tried doing what he knew John would want him to do. He'd said hello. Introduced himself. Even offered a short autobiography; his age, occupation, and how he'd come to meet John. Informed him that he would care for and protect him until Sherlock gasped his very last breath.

What had he gotten in return? A gurgling noise, a brief grin, and a mere eight-point-five seconds of eye contact.

Hardly what he would classify as a 'meaningful conversation'.

"If that's the case…" he heard John saying, and looked up. "If he _is_ mine…" A little quirk of his eyebrow. "Then simple rules of mathematics make him yours, too, you know."

Sherlock frowned. "How so?"

John gave him a look that said '_you're the ridiculous genius in our family. Figure it out for yourself_'.

It didn't take him long.

Sherlock smiled, and looked from John, to their son, and back again. "The transitive relation."

"Exactly."

…Their son belonged to John. John belonged to Sherlock. Therefore, their son belonged to Sherlock.

Sentiment- a weakness that John had managed to infect him with after eight years, although fortunately only on a sporadic basis -must've slowed down his thought processes, because when he ran the notion through in his mind a second time, the consulting detective just laughed. "You do realize, of course, that such a statement is actually meaningless from a biological standpoint?"

"Yes, Sherlock. I, _Doctor_ John Watson do realize that biologically, he can only belong to one of us." Reaching over, he threaded his fingers through Sherlock's mop of hair. Those strong, rounded digits found themselves purposely tangled in his dark curls, and massaged into his scalp. Causing a wave of heat to ripple down into his stomach. "What I'm saying though is that the biology doesn't really enter into it. Not where it counts." A soft sigh from John. One of contentment, of pride. "You, Sherlock Holmes, are now a father."

As if he were doing it to help prove the other man's point, a tinier row of fingers planted themselves on Sherlock's bottom lip right then. Four little twigs pressed into the fleshy pad, and his thumb hooked underneath. Holding one half of Sherlock's mouth hostage.

Glancing down, he was ensnared by his son's gaze. Suddenly more intense than it had been just a short while ago. Deep and blue, like the Atlantic Ocean in the middle of a storm. Glimmering with a look of bewilderment. Fascination. A few long seconds of this, and suddenly the storm cleared. Their son's eyes brightened up, and he giggled. A short, explosive row of joyful bubbles that popped out of him.

Something growled to life in Sherlock's chest at that. Something warm and electric. Fluttering around in the apices of the ventricles of his heart, before being ejected out into his lungs and systemic circulation. Making his breath catch, and every sinew of his muscles shudder with bliss.

He felt his eyebrows twitch into a frown, as he struggled to comprehend the feeling that was now ricocheting throughout his insides. Looking across to John, he just gave him a helpless smile. "Yes…" he said, voice low and a bit shaky. "Yes, I… I suppose I am."

[-_End_-]


End file.
